Many types of input devices are presently available for performing operations in a computing system, such as buttons or keys, mice, trackballs, joysticks, touch sensor panels, touch screens and the like. Touch screens, in particular, are becoming increasingly popular because of their ease and versatility of operation as well as their declining price. Touch screens can include a touch sensor panel, which can be a clear panel with a touch-sensitive surface, and a display device such as a liquid crystal display (LCD) that can be positioned partially or fully behind the panel so that the touch-sensitive surface can cover at least a portion of the viewable area of the display device. Touch screens can allow a user to perform various functions by touching the touch sensor panel using a finger, stylus or other object at a location dictated by a user interface (UI) being displayed by the display device. In general, touch screens can recognize a touch event and the position of the touch event on the touch sensor panel, and the computing system can then interpret the touch event in accordance with the display appearing at the time of the touch event, and thereafter can perform one or more actions based on the touch event.
Mutual capacitance touch sensor panels can be formed from a matrix of drive and sense lines of a substantially transparent conductive material such as Indium Tim Oxide (ITO), often arranged in rows and columns in horizontal and vertical directions on a substantially transparent substrate. In some touch sensor panel designs, the substantially transparent drive lines can be routed to one edge of the substrate for off-board connections using conductive (e.g. metal) traces in the border areas of the substrate where transparency is not required. These conductive traces can be formed by depositing or otherwise forming layers of conductive material on the substrate. The conductive traces can then be protected by passivation layers. Passivation layers are often inorganic compositions (e.g. silicon dioxide (SiO2) or silicon nitride (SiNx)) formed over conductive material such as ITO and other layers to protect those materials from corrosion and other environmental effects. These inorganic compositions are typically formed from simple, small molecules and can be applied using techniques such as sputtering. However, even with the addition of a passivation layer, there are reliability issues involved in the fabrication of these conductive traces.